Ultra-high-strength sulfoaluminate cement can play a good role in cement self-leveling mortar: increase surface mechanical strength; improve early strength; reduce shrinkage, control cracking; improve surface decoration effect, good coloring power; improve fluidity at a certain dosage.
In the Portland cement-ultra-high-strength sulphoaluminate cement-gypsum ternary system, no matter whether Portland cement or ultra-high-strength sulphoaluminate cement is the main component, as long as the proportion is appropriate, the compound with excellent performance can be formulated. self-leveling mortar. In contrast, the self-leveling mortar based on Portland cement has a longer setting time, and the initial setting is generally 70 minutes to 120 minutes. It is suitable for preparing and pouring thicker self-leveling mortar to ensure sufficient working time and longer time. good mobility. The self-leveling mortar based on ultra-high-strength sulfoaluminate cement has a short setting time, and can generally be set and hardened within 30 minutes to 60 minutes. It is very suitable for thin-layer self-leveling and projects that require high early strength.
In the process of practical application, it was found that due to the limitation of the site conditions, many ground bases have no waterproof layer, some side walls have leakage, and some projects are old house renovations, and the base layer has a lot of moisture, which far exceeds the humidity requirement. Under such circumstances, a short expansion stability period is especially important for self-leveling mortar, and the addition of ultra-high-strength sulfoaluminate cement successfully solves this problem. The appearance of ultra-high-strength sulfoaluminate cement is yellow-white, and the material color is improved in the ternary system (especially ultra-high-strength sulfoaluminate cement), which has a good decorative effect, especially in the preparation of colored cement self-leveling mortar, the effect is better.
Ultra-high-strength sulfoaluminate cement has early-strength and rapid-hardening properties, and can be formulated with rapid-hardening tile adhesives. Adding it to jointing agent can compensate for shrinkage and effectively prevent alkali return. Since C2S and C3S in Portland cement generate hydration C-S-H, they also produce a large amount of Ca(OH)2, which is a highly deliquescent substance that migrates to the surface of the mortar and the air with the evaporation of water. The CO2 in the reaction produces CaCO3 and returns to alkali. After the introduction of ultra-high-strength sulfoaluminate cement, 3CaO·3Al2O3·CaSO4 is excited by Ca(OH)2 and CaSO4 to produce ettringite Aft expansion crystals to fill in capillary pores and cracks, preventing free water from seeping out, playing the role in inhibiting reversion to alkalinity.
